Polydicyclopentadiene (PDCPD) is a heavily crosslinked organic polymer produced by ring-opening metathesis polymerization (ROMP) of dicyclopentadiene. Crosslinked PDCPD has a very high impact resistance (due to the extensive crosslinking), coupled with a large resistance to chemical corrosion (particularly if the alkenes in the final structure are hydrogenated), and a high heat deflection temperature. These properties make PDCPD attractive for use in the automotive industry. After initially being used to make cowlings for snowmobiles (due to its high impact resistance at low temperatures), PDCPD is now used to make body panels, bumpers and engine blocks or components for trucks, buses, tractors and construction equipment. In addition to these automotive applications, PDCPD components are used in the chlor-alkali industry, both as storage tanks for corrosive chemicals, and as cell covers for electrolyzers.
One significant limitation to polydicyclopentadiene, however, is a lack of chemical tunability, owing to the unfunctionalized homodimeric monomer feedstock. Thus, whereas polymers of functionalized ethylene (e.g. propylene, styrene, acrylic acid, methyl acrylate, acrylonitrile, methyl methacrylate, vinylidene chloride, etc.) exhibit a broad range of very distinct and very useful material properties, no such variability can be readily obtained for PDCPD-based polymers.
A second related limitation for polydicyclopentadiene concerns its lack of recyclability. As is the case with most thermoset polymers, the crosslinks in PDCPD are chemically irreversible. Due to this irreversibility, there exists no convenient way to recycle PDCPD products that have reached the end of their useful lifetimes back to a processable form, so that the material can be re-used for new products. This, combined with PDCPD's lack of malleability at high temperatures, makes the current generation of PDCPD products a material dead-end.
A third current limitation for polydicyclopentadiene (once again owing to its lack of chemical tunability) relates to the low surface energy of the polymer. This makes it difficult to robustly bond other parts to objects made from PDCPD, without resorting to separate air oxidation steps and/or lengthy adhesion protocols (often requiring specialized equipment).
Given increasing consumer and legislative demands for product recyclability, the continued growth of the PDCPD industry is unsustainable without a long-term solution to the problem of material recycling. This is true even as the automotive industry looks to replace increasing amounts of metal parts with lighter weight polymer materials; while PDCPD would be ideal for many of these applications, the current pressures from regulatory agencies like the US government to ensure that a larger percentage of automotive plastics can be recycled at the end of the vehicle's useful lifetime will make non-recyclable PDCPD an unsuitable choice. As such, there exists a need in the art for new forms of functionalized polydicyclopentadiene (also referred to as “fPDCPD”), the creation of a truly recyclable form of PDCPD, and the ability to modify the surface energy of the polymer in a consistent and controllable fashion.